This is an excellent question as there is great variability in what truly constitutes “free range.” Often, this simply means that the chickens will have access to going outside, but they may not. And, as you point out, they may still be fed with grains like GMO corn. Eggs from truly “free-range” chickens are not “fed” anything.  The best name to look for would be “pasture raised” as these chickens seem to spend the most time eating their natural food.  I agree that eating eggs from chickens fed grains poses a concern.